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- @atten gisten getest @ffirsQ j E. s. GHAPELL, or MILTON, MASSACHUSETTS- i; Letters Patent No. 68,488, dated September 3, 1867.

IMPROVED BORING-BAR FOR-BORING AND SCREW-CUTTING.

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TO ALL WHOM IT MAY CONCERN: j

Be it known that I, E. S. CHAPELL, of Milton, in the county' of Norfolk', and State of Massachusetts, have invented a new and improved Eccentric Boring-Bar for Screw-Cutting; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable others skilled in the art to make and use the same, reference being had to the accompanying drawings, forming part'ot' this specification, in which- Figure 1 represents my improved bo ring bar partly in :longitudinal section.

Figure 2, an end View', with the lever detached.

Figure 3, a detached view of the worm gear.

Figure 4, a detached 'view of the lever.

Similar letters of reference indicate like parts.

'This invention relates to an improved construction of a boring-bar for cutting threads in` nuts or internal screw-cutting, and consists in a round harwith eccentriccentresvor turning points in the ends, provided with a,

r head sliding and turning freely thereon, as hereinafter more particularly described.-

A represents the round boring-bar, and B the sliding-head, fitted on it to move and turn freely. The bar is countersunk at the ends with holes a a, outside of-its centre, sothat when it is set on theccntres of a lathe, and the block is firmly screwed in the tool-post, the boring-bar becomes an eccentric, while the head B slides freelywith the carriage ot' the lathe. At one end of the head B a cutter, b, is firmly secured,and at thcother end is a projecting arm, e, on which'is a slotted block, d, that admits of some motion on the arm except from right to left, and eine versa. A bracket,pe, is also attached to the same end of the head on the opposite side to the arm c, which carries a worm, g, and a hand-wheel, h, on the same shaft c. The arm e serves to connect the sliding-head B with the carriage of the lathe, on whose centres thc eccentric bar is supposed to bc placed, as shown in red, iig. 2, '.lhe block d is slotted in such a manner as te allow the arm c to accommodate itself tothe eccentric motion of the head, while the block d is firmly secured in the tool-post of the carriage of the lathe, and when so secured the head B has a longitudinal motion without backlash, uniform with the tool-post and carriage, and derives the feed-motion from On the boring-bar is a hub, m, that is prevented from turning by a feather sliding in a groove in the bar. The hub m carries a worm-gear, g', which is prevented from turning completely round by Aa spur, z', on the feather that projects through the hub into a groove, s, iig. 3, of about half a circle in the worm-gear. The-worm-gear g is secured on the hub m'by a nut, n, which fixes the gear in any position, by being screwed up tight. A projection, p, 'on the 4inside ofthe bracket e, works in a groove in the hub, and insures the uniform movement of the hub and head. A lever, g, is also .fitted on the end of the boring-bar, which may be clamped in any position on the bar. I

In boring plain work chncked on the face-plate of a lathe, the cutter I) may be adj usted within the limits of the throw'ot` the eccentric boring-bar by' turning the bar with'the lever q, and when so adjusted may be' secured by the nut n on the hub. But it is in internal screw-cutting that this eccentric boring-bar is particularly applicable and-useful, the worm and gear serving to gauge the successive cuts required, while the eccentric bar throws the cutter in and out of the thread with great facility. Also, in boring collar-thrust bearings, the worm and gear serve as a feed for squaring up the sides of the collars. The bar may also be made to revolve, while the work is firmly bolted to the carriage, with equal facility.

Thisimproved boring-bar is especially designed for heavy Steamship and other machinery, cutting nuts for securing the pistons on the rods and collar-thrust bearings of the largest size.

Having described myinrention, I claim as new, and desire to secure by Letters Patent- The eccentric sliding boring-bar A, in combination with the worm and gear g g', and lever q, constructed, arranged, and operating substantially as and for the purposes herein described.

E. S. CHAPELL.

Witnesses: i

Josrnn Ween, C. H. WEBB. 

